1. Field of the Invention
This invention relates generally to systems and methods for prompting patient, and more specifically, to systems and methods for prompting patient to control patient movement.
2. Background of the Invention
Computed tomography is an imaging technique that has been widely used in the medical field. In a procedure for computed tomography, an x-ray source and a detector apparatus are positioned on opposite sides of a portion of a patient under examination. The x-ray source generates and directs a x-ray beam towards the patient, while the detector apparatus measures the x-ray absorption at a plurality of transmission paths defined by the x-ray beam during the process. The detector apparatus produces a voltage proportional to the intensity of incident x-rays, and the voltage is read and digitized for subsequent processing in a computer. By taking thousands of readings from multiple angles around the patient, relatively massive amounts of data are thus accumulated. The accumulated data are then analyzed and processed for reconstruction of a matrix (visual or otherwise), which constitutes a depiction of a density function of the bodily section being examined. By considering one or more of such sections, a skilled diagnostician can often diagnose various bodily ailments such as tumors, blood clots, etc.
Computed tomography has found its principal application to examination of bodily structures or the like which are in a relatively stationary condition. However, currently available computed tomographic apparatus may not be able to generate tomographic images with sufficient quality or accuracy due to physiological movement of a patient. For example, beating of a human heart and breathing have been known to cause degradation of quality in CT images.
Degradation of quality of CT images due to patient's breathing is more difficult to address than that associated with heart motion. Patients' breathing poses a unique problem to CT imaging that is different from heart motion. This is because the pattern and the period of a patient's breathing cycle is generally less consistent when compared to those of the patient's cardiac cycle. As such, while a particular phase of a cardiac cycle may be predicted with sufficient accuracy, a particular phase of a breathing cycle may not be as easily predicted or determined. Furthermore, there has been an increased desire to visualize organ motion by viewing a sequence of CT images as a movie sequence. However, collecting a large quantity of CT image data sufficient for forming a video while considering breathing motion is difficult to perform and may take a much longer time.
For the foregoing, it would be desirable to prompt a patient to control the patient's breathing as CT image data are collected. The controlling can be in the form of 1) issuing periodic visual and audio commands to regularize the respiration motion so that a CT sequence can be formed as a function of the phase of breathing, or 2) using visual and audio commands to prompt the patient to hold breath at specific times and periods as required by the image acquisition process. Although visual signals have been used to prompt patients, use of visual prompting signals have been avoided in radiation procedures. This is because most image devices, such as a computer screen, is too large to fit within the bore of a CT machine. Even for those image devices that could fit within the bore of a CT machine, the image device will take up a lot of space within the bore. This may cause a patient who is confined within a gantry opening to feel uncomfortable—especially if the patient is claustrophobic. Also, electronics of an image device may interfere with a radiation field generated during a CT procedure.